This invention relates to bladeless shearing of linear stock such as stainless steel tubing and bar stock and, more particularly, to a device which achieves the shearing of stock by causing elliptical, lateral translation of a section of the stock relative to an axially adjacent section.
In U.S. Pat. No. 4,635,514 xe2x80x9cElliptical Shearing Apparatusxe2x80x9d, issued Jan. 13, 1987 to Alexander Borzym, there is disclosed a bladeless device for shearing linear stock, such as bar stock and tubing, by causing a section of the stock to translate laterally through an elliptical path relative to the axially adjacent stock. As is more fully disclosed in the aforesaid patent, this is achieved through the use of a large, steel body referred to as a xe2x80x9cdie holderxe2x80x9d having a central, die-like aperture formed therein which is adapted to receive and precisely surround the linear stock. One side of the die holder is pinned to permit pivotal and limited lateral motion. The other side is connected to a drive mechanism consisting of a large electric motor driving a flywheel at constant speed and a clutch and brake mechanism for selectively and momentarily imparting orbital motion to the die holder. Orbital motion of the die holder around the mechanical drive center produces a unidirectional, elliptical translation of the stock receiving die which lies between the drive center and the pinned end of the die holder. The amplitude of the elliptical motion is a function of the amplitude of the orbital drive motion and the geometric location of the die within the die holder body.
By placing a fixed die also having a stock-receiving aperture immediately axially adjacent to the moveable die, a scissors-like shearing action is produced on a length of stock which is inserted through the two aligned dies; the shear line is defined by the mating plane of the two dies.
There are numerous advantages to a shear of this type relative to cutoffs using blades or other cutting implements. The principal advantages are the elimination of the cutting implement as a perishable component and the conservation of material in the work piece; i.e., saw blades and guillotine blades remove a section of material approximately equal to the thickness of the blade each time it passes through the stock. The resulting loss of material from the stock is significant, particularly where short lengths and high cutting rates are employed.
Another advantage is the quality of the xe2x80x9ccutxe2x80x9d which can be achieved in the use of the bladeless shear in connection with stock of very hard material such as stainless steel. Blade type cutoffs are known to cause distortion; e.g., burrs and/or dents in the cut tube ends, and very high blade wear when used with hard materials such as stainless steel. The bladeless shear cutoff actually excels when used with materials of this type.
The present invention provides a novel and advantageous table suitable for supporting lengths of tubular stock of varying diameters being fed into a supported shear where the tubular stock is severed into desired lengths. The table comprises a pair of parallel spaced apart rods, preferably of cirular cross section, symmetrically arranged on opposite sides of the intended path of the stock. The rods are pivotally connected to links which in turn are pivotally connected to converging surfaces of a support block such that coordinated rotation of the links changes the spacing between the support rods without disturbing the parallel relationship between them.
In the preferred embodiment, the angular positions of the links are determined by turnbuckles which are connected between the tops of the links and a support block which can be clamped to a support surface in any of an infinite number of longitudinal positions such that angular position of the links can be controlled either by adjusting the turnbuckles or adjusting the clamp block.